[202012][submodule] Update sonic-swss submodule

Update sonic-swss submodule pointer to include the following:
* VxLAN Tunnel Counters and Rates implementation (sonic-net#1859) ([sonic-net#2442](sonic-net/sonic-swss#2442))
* Update fdborch.cpp ([sonic-net#2374](sonic-net/sonic-swss#2374))

Signed-off-by: dgsudharsan <sudharsand@nvidia.com>